Commercially, the recovery of carbon monoxide from waste gas stream is carried out by cryogenic methods or by means of the "Cosorb" process. The latter process uses cuprous aluminum chloride in toluene solvent to adsorb CO from gas mixtures at ambient temperatures and at pressures of less than 20 atmospheres. The principal disadvantage of this process is decomposition of the adsorbent by water vapor or by sulphur compounds which must therefore be reduced to levels on the order of 1 ppm. Other adsorbent solvent systems for the recovery of CO from gas mixtures are known in the patent literature such as liquid fluorocarbons (U.S. Pat. No. 3,762,133) and cuprous fluoroborate dissolved in toluene (U.S. Pat. No. 3,060,676). These processes are subject to similar problems. Additionally, solvent vapors carried over by the unabsorbed gases and by desorbed CO during thermal desorption must be recovered.
In view of the prior art difficulties mentioned above, it would be advantageous to have a solid adsorbent system for CO recovery. A number of such adsorbents are known for this purpose. For example, active carbon, molecular sieves or silica gel having been used to adsorb CO from gas mixtures using a pressure swing adsorption process when H.sub.2 is the major contaminating gas. However, the process employing these adsorbents generally does not produce high purity CO and is useful only for H.sub.2 containing CO streams in which the CO is present at low concentrations and only high purity H.sub.2 is desired.
It is an object of the present invention to produce an adsorbent for CO which is not destroyed on contact with water, which is thermally stable to allow for thorough stripping of adsorbent gas and which will adsorb CO in nitrogen rich gas streams such as those produced by blast oven furnaces.